Deorbiting a dead satellite normally costs propellant the satellite often no longer has. A tether offers a propellant-free alternative. US12330817B1, granted to Excalibur Almaz USA, Inc. on June 17, 2025, claims "tether-based reaction control and orbital energy reduction" to do exactly that.
The CPC is striking in its economy: B64G 1/623, the classification for arrangements for deorbiting or re-entry of spacecraft. A single, on-point code — the mark of a focused deorbit claim. (A companion grant, US12286245B2 from April 2025, carries essentially the same disclosure.)
The mechanism is electrodynamic and aerodynamic drag, harnessed. A long conductive tether deployed from the spacecraft moves through Earth's magnetic field, and a current induced in it produces a drag force (the electrodynamic effect); a tether also increases aerodynamic drag in the thin upper atmosphere. Both effects bleed orbital energy, gradually lowering the orbit until the spacecraft re-enters. Critically, this happens without firing a thruster — no propellant, no propulsion system that has to still be alive at end of life.
For the debris-mitigation problem, that propellant-free property is the whole appeal. Regulators increasingly demand timely disposal, and a passive or near-passive deorbit device that does not depend on surviving propulsion is an attractive compliance tool — especially designed in from the start as a dedicated end-of-life system.
The discipline this desk applies to every frontier claim: electrodynamic and drag tethers have a long research history and have flown only in limited demonstrations, with deployment reliability a persistent challenge. This protects Excalibur Almaz's specific tether-based reaction-control-and-deorbit approach, not tethers in general, and a granted claim is not a proven operational device. Read it as one concrete entry in the deorbit-technology whitespace — and a reminder that the hard part of tethers has always been deploying and controlling them, which is exactly what the apparatus claims must earn in flight.